1. Field of the Invention
The present invention relates to an image capturing unit which includes an optical element which makes use of electrocapillarity and an image capturing device.
2. Description of Related Art
In a conventional image capturing device such as a video-camera, some optical system can change a focal length. Most of these optical system change the focal length by moving a part of lenses or a part of lens group mechanically. Also, there has been invented a variable focal-length lens which can change the focal length by varying an optical characteristics in the lens. For example, there is a variable optical element which makes use of electrocapillarity.
Such a variable optical element is commonly known which is provided with a container for containing a first liquid member and a second liquid member which does not mix in the first liquid member. Also, such a variable optical element is provided with a first ring electrode which surrounds the first liquid member and a second ring electrode which surrounds the second liquid member. Here, an interfacial shape between the first liquid member and the second liquid member is varied according to a voltage which is applied to the liquid members (see “Robert E. Fischer, Current Developments in Lens Design and Optical Engineering III, U.S.A., SPIE, July 2000”). Also, various optical systems which are provided with such a variable optical element have been proposed (see page 16, FIG. 6 in Japanese Unexamined Patent Application, First Publication No. 2001-249203, and page 16 and FIG. 7 in Japanese Unexamined Patent Application, First Publication No. 2001-249261).